1 /* @(#)s_nextafter.c 5.1 93/09/24 */ 2 /* 3 * ==================================================== 4 * Copyright (C) 1993 by Sun Microsystems, Inc. All rights reserved. 5 * 6 * Developed at SunPro, a Sun Microsystems, Inc. business. 7 * Permission to use, copy, modify, and distribute this 8 * software is freely granted, provided that this notice 9 * is preserved. 10 * ==================================================== 11 */ 12 13 /* IEEE functions 14 * nextafterl(x,y) 15 * return the next machine floating-point number of x in the 16 * direction toward y. 17 * Special cases: 18 */ 19 20 #include <sys/cdefs.h> 21 #include <math.h> 22 23 #include "math_private.h" 24 25 long double 26 nextafterl(long double x, long double y) 27 { 28 int64_t hx,hy,ix,iy; 29 u_int64_t lx,ly; 30 31 GET_LDOUBLE_WORDS64(hx,lx,x); 32 GET_LDOUBLE_WORDS64(hy,ly,y); 33 ix = hx&0x7fffffffffffffffLL; /* |x| */ 34 iy = hy&0x7fffffffffffffffLL; /* |y| */ 35 36 if(((ix>=0x7fff000000000000LL)&&((ix-0x7fff000000000000LL)|lx)!=0) || /* x is nan */ 37 ((iy>=0x7fff000000000000LL)&&((iy-0x7fff000000000000LL)|ly)!=0)) /* y is nan */ 38 return x+y; 39 if(x==y) return y; /* x=y, return y */ 40 if((ix|lx)==0) { /* x == 0 */ 41 volatile long double u; 42 SET_LDOUBLE_WORDS64(x,hy&0x8000000000000000ULL,1);/* return +-minsubnormal */ 43 u = x; 44 u = u * u; /* raise underflow flag */ 45 return x; 46 } 47 if(hx>=0) { /* x > 0 */ 48 if(hx>hy||((hx==hy)&&(lx>ly))) { /* x > y, x -= ulp */ 49 if(lx==0) hx--; 50 lx--; 51 } else { /* x < y, x += ulp */ 52 lx++; 53 if(lx==0) hx++; 54 } 55 } else { /* x < 0 */ 56 if(hy>=0||hx>hy||((hx==hy)&&(lx>ly))){/* x < y, x -= ulp */ 57 if(lx==0) hx--; 58 lx--; 59 } else { /* x > y, x += ulp */ 60 lx++; 61 if(lx==0) hx++; 62 } 63 } 64 hy = hx&0x7fff000000000000LL; 65 if(hy==0x7fff000000000000LL) return x+x;/* overflow */ 66 if(hy==0) { 67 volatile long double u = x*x; /* underflow */ 68 } 69 SET_LDOUBLE_WORDS64(x,hx,lx); 70 return x; 71 } 72 73 __weak_alias(nexttowardl, nextafterl); 74